Features

Integration Instructions

The .NET CAS client integrates with ASP.NET applications by customizing the application web.config file. The client is implemented as an ASP.NET IHttpModule, CasAuthenticationModule, that provides hooks into the ASP.NET request/response pipeline through lifecycle events. This provides a familiar configuration path for client integration, including the following:

The CasAuthenticationModule must be made available to the application via the familiar process for .NET assemblies; either of the following is sufficient:

Ensure it is deployed to the /Bin directory of the Web application

Add it to the .NET Global Assembly Cache

Configure CasAuthenticationModule

Define the casClientConfig configuration section:

Register casClientConfig Section

Place a <casClientConfig> configuration element directly under the root <configuration> element. The position of the <casClientConfig> element in the web.config file is unimportant.

Demonstrative casClientConfig

The following attributes are supported in the casClientConfig configuration section.

casServerLoginUrl REQUIRED URL of CAS login form.

serverName REQUIRED Host name of the server hosting this application. This is used to generate URLs that will be sent to the CAS server for redirection. The CAS server must be able to resolve this host name. If your web application is behind a load balancer, SSL offloader, or any other type of device that accepts incoming requests on behalf of the web application, you will generally need to supply the public facing host name unless your CAS server is in the same private network as the application server. The protocol prefix is optional (http:// or https://). If you are using a non-standard port number, be sure to include it (i.e., server.school.edu:8443 or https://server.school.edu:8443). Do not include the trailing backslash.

casServerUrlPrefix REQUIRED URL to root of CAS server application.

ticketValidatorName REQUIRED Name of ticket validator that validates CAS tickets using a particular protocol. Valid values are Cas10, Cas20, and Saml11.

renew OPTIONAL Force user to reauthenticate to CAS before accessing this application. This provides additional security at the cost of usability since it effectively disables SSO for this application. Default is false.

singleSignOut OPTIONAL Enables this application to receive CAS single sign-out messages sent when the user's SSO session ends. This will cause the user's session in this application to be destroyed. Default is true.

ticketTimeTolerance OPTIONAL Adds the given amount of tolerance in milliseconds to the client system time when evaluating the SAML assertion validity period. This effectively allows a given amount of system clock drift between the CAS client and server. Increasing this may have negative security consequences; we recommend fixing sources of clock drift rather than increasing this value. This configuration parameter is only meaningful in conjunction with ticketValidatorName="Sam11".

notAuthorizedUrl OPTIONAL The URL to redirect to when the request has a valid CAS ticket but the user is not authorized to access the URL or resource. If this option is set, users will be redirected to this URL. If it is not set, the user will be redirected to the CAS login screen with a Renew option in the URL (to force for alternate credential collection).

serviceTicketManager OPTIONAL The service ticket manager to use to store tickets returned by the CAS server for validation, revocation, and single sign out support. Without a ticket manager configured, these capabilities will be disabled. Valid value is CacheTicketManager.

proxyTicketManager OPTIONAL The proxy ticket manager to use to maintain state during proxy ticket requests. Without a proxy ticket manager configured your application will not be able to issue proxy tickets.

gatewayStatusCookieName OPTIONAL The name of the cookie used to store the Gateway status (NotAttempted, Success, Failed). This cookie is used to prevent the client from attempting to gateway authenticate every request. Default value is cas_gateway_status.

cookiesRequiredUrl OPTIONAL The URL to redirect to when the client is not accepting session cookies. This condition is detected only when gateway is enabled. This will lock the users onto a specific page. Otherwise, every request will cause a silent round-trip to the CAS server, adding a parameter to the URL.

Register CasAuthenticationModule

Register CasAuthenticationModule with the ASP.NET pipeline by adding it to the <system.web><httpModules> and <system.webServer><modules> sections as demonstrated in the following configuration blocks.

Register with httpModules Section

Register with modules Section

Configure ASP.NET Forms Authentication

Configure the ASP.NET Forms authentication section, <forms>, so that it points to the login URL of the CAS server defined in the casServerLoginUrl attribute of the casClientConfig section. It is vitally important that the CAS login URL is the same in both locations.

Configure Forms Element

Configure Authorization

Configure authorization roles and resources using the familiar ASP.NET directives. We recommend the user of a role provider that queries a role store given the principal name returned from the CAS server. There is not support at present for extracting authorization data from the attributes released from CAS via the SAML protocol.

Configure Diagnostic Tracing (optional)

CasAuthenticationModule uses the .NET Framework System.Diagnostics tracing facility for internal logging. Enabling the internal trace switches should be the first step taken to troubleshoot integration problems.

TRACE Compiler Option

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System.Diagnostics tracing requires that the source be compiled with the /TRACE compiler option in order to produce output to trace listeners. The binary distributions of CAS provided here are compiled in DEBUG mode with the /TRACE option enabled.

The following web.config configuration section provides a sample trace configuration that should be used to troubleshoot integration problems.

The configuration above will produce trace output to the file C:\inetpub\logs\LogFiles\DotNetCasClient.Log. This file path is only representative; a convenient and accessible path should be chosen based on deployer requirements.

File Permissions

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The application pool in which the CAS-enabled .NET application runs must execute under a user with permission to create and write the trace log file.

User support is provided via the CAS user mailing list, cas-user@lists.jasig.org. Feature requests may be discussed on the user or dev (cas-dev@lists.jasig.org) mailing lists, or created directly in the project Jira space, NETC.

I've been trying to reproduce the example with the web application that comes in the "dotnet-client-1.0-Src.zip" file. I added the web application to an IIS 7 and I'm always getting the same error. This is the code of the error: 0x80070021.

I've tried to fix it following some advices that I found on Google (like putting overrideModeDefault="Allow"), but it doesn't work. Can someone help me??? Thanks.

While working with the DotNetCasClient I've notice that when setting the ticketValidationName = "Cas20", no attributes are coming through. With further investigation I've found that in the method ParsResponseFromServer in the Cas20ServiceTicketValidator class, it is only parsing the user name and testing if the user has been CAS authenticated and omitting the attributes all together. Was there a reason for not parsing the response xml to get the attributes? Will Cas20 support attributes in next releases?

I have set up the CAS .NET client as instructed in this Wiki, however when a user enters their credentials into the CAS logon page they get redirected back to the logon page, rather than to our web application.

We have experimented with the php CAS client, using the same CAS instance and redirection is working nicely. We noticed that the query string passed to the CAS logon page is different when using the .NET client; the redirect URL query string parameter has a name of TARGET, whereas when using the php CAS client it has a name of service. Is this significant?